Question: There are 3 complex numbers $a+bi$, $c+di$, and $e+fi$. If $b=1$, $e=-a-c$, and the sum of the numbers is $-i$, find $d+f$.
Answer: We know that $a+bi+c+di+e+fi=-i$. Thus, the real parts add up to 0 and the imaginary parts add up to -1. We then have  \begin{align*}
a+c+e&=0\\
b+d+f&=-1\\
\end{align*}We know that $b=1$, therefore $d+f=\boxed{-2}$